Drilling bore holes



Jan. 9, 1951 Filed Aug. '7, 1947 HEIGHT OF HEAVY dopuvm IN ANNLJLUS B.W. SEWELL DRILLING BORE HOLES 5 Sheets-Sheet l DRILL. 0LLA2 E RAT EDCORE DEFLECTOP... TubE HEJGHT o|= HEAVY COLUMN m :DlzmL PIPE 2 *sg gii--E er2jamurz iJf'sew-aLL fiavenbor b g L (2 CLbboFn-ag Jan. 9, 1951Filed Aug. 7, 1947 B. w. SEWELL DRILLING BORE HOLES MUD 12 @QORE. STOPcola '3 Sheets-Sheet 2 Fray-4 Ciubor'nas Jan. 9, 1951 B. w. SEWELL2,537,605

DRILLING BORE H Es Filed Aug. 7, 1947 3 Sheets-Sheet 5 21 1' 3.1."; 4FROM DUMP AEJZAT an MUD FIGrES .bergjcmtn CJ'Sew-dZ CSrzvenoor Clbbornag/S- Patented Jan. 9, 1951 DRILLING'VBORE HOLES Benjamin W. Sewell',llulsa, kla., assignor to Standard: Oil Beveloprnent Company, acorporation of Delaware Application August 7, 1947, Serial No. 766,934

permits a continuous coring of the formation penetrated by the-borehole.

In the conventional rotary drilling process a hollow drill pipe carryinga drill bit is caused to penetrate the earth while maintaining acirculation of drilling fluid downwardly through the inside of the drillpipe, out through suitable eyes inv the drill bit and up through theannular space between the drill pipe and the borehole wall to thesurface where it is discharged into a: pit for the settling of cuttings.This drilling fiuid is then pumped from the setting pit-to the upper"end or" the drill pipe. This method of drilling, by reason of thedirection of circulation of the drilling fluid, makes it impossible toobtain continuous cores of the formations penetrated. Moreover, in thismethod the upward flow of drilling fluid through the annularspa-cementioned above frequently develops rather high velocity whichtends to cause sloughing of the bore hole wall.

According to the present invention the rotary drilling method isimproved, first, by reversing the direction of flow of the drillingfluid so that it flows downwardly through the space between the drillingpipe and the borehole wall and upwardly through the drill stem. This initself is not a new expedient. In previous embodiments, however, thecirculation of the drilling fiuid has been a forced circulation inducedby applying pressure to the mud column in the annular space. Thispressure tends to accelerate filtration of the fluid into porousformations and also to increase lost returns. According to the presentinvention these diffi-culties are avoided by merely maintaining theannular space full of fluid and inducing circulation by aerating the mudcolumn inside the drill pipe for an appropriate distance below its topto create the necessary difierential in pressure head between thecolumns outside arid inside of the drill pipe to cause flow upwardlythrough the drill pipe.

The principal object of the presnt invention is to provide a rotarymethod for drilling bore holes in which the conventional flow of fluidis reversed with the column of fluid outside the drill stem existingunder its own hydrostatic pressure.

An additional object of the present invention is the provision of amethod and apparatus of the character described in which provision ismade for the collection of a limited number of cores during the drillingoperation, which cores may be brought to the surface.

2 Claims. (01. 255--24) A more specific object of the invention is theprovision of a method and-apparatus of the character described by whicha bore hole may be drilled and continuous cores of the formationspenetrated brought to the surface and recovered without interrupting thedrilling operation.

A more specific object of the present invention is the provision inapparatus of the character described of means for breaking up acontinuous core into relative short sections so that. they may readilyflow to the surface.

Further advantages of the present. invention will appear in thefollowing detailed description of the-accompanying drawing, in which.

Figure-1 is-a vertical sectionof a bore hole with an embodiment of thepresent invention in opera.- tive position and partly in section;

Figure 2 is a similar view of a modified form of the present invention;

Figure 3 is a similar view of still another embodiment of the present.invention;

Figure 4 is anenlargement of Aeof Figure 3; and V Figure 5- is avertical section of. an alternative form of the arrangement shown at thebottomof the drill stem in Figure 3.

Referring to the drawing in detail, numeral I designates the earthpenetrated a bore hole in which is" arranged a. drill stem 3 carrying aconventional drill bit 4.. The upper end of the drill stemis providedwith the usual Kelly 5 havinga swivel joint 6. It will be. understoodthat the Kelly is a pipe of non-circular cross section andpasses througha correspondingly shaped hole in the rotary table. The swivel jointabove I the Kelly is provided with the usual line "i which in this caseis used to conduct drilling fluid into the mud pit instead of passing.it down, through the drill stem. Extending down. into. the drill. stemis a pipe 8 whichat its lower end, is provided with a distributing head9. This pipe extends down into the drill stem a distance selected togive a rate ofv fiow desired in the circulating drilling fluid stream.In other words the higher the rate desired, the farther down into thedrill pipe this line-9 is extended. Thedrilling mud is..returned fromthe mud pit to the annular spacebetween the bore hole and the drillstern. bye. pipe Ill which. ordinarily can be an open ended pipe.

discharging into said annular space at a. ratesufficient. to keep saidspace full of drilling fluid.

In operating according. to the present invention, the annular space andthe drillv pipe are filled with drilling fluid andcirculation is startedby starting the flow of gas through pipe 8. The

velocity of flow of the gas for a given position of the pipe 8 and for agiven drilling mud will determine the rate of circulation of drillingmud. Thus the operator has two controls over this rate of circulation.For best results, according to the present invention, it is preferredthat the vis cosity of the fluid be adjusted to between about 10 and 30centipoises and that its gel strength be maintained at a suficiently lowlevel to readily release the gas introduced through line 8 when it isdischarged into the mud pit. It will be appreciated that the drillingmud can be constantly or periodically treated with chemicals commonlycalled defiocculating or peptising agents such as sodium tannate, sodiumphosphate, sodium pyro-phosnhate, sodium metavanadate and the like whichtend to hold down or reduce the viscosity of the drilling fluid so thatit will readily release gas.

In the embodiment shown in Figure 2 the drill stem is provided at itslower end with a core receptacle l I at the upper end of which is a stopl 2 having suitable passages Is for the circulation of the drillingfluid. In this case the drill bit it em loyed is a conventional core bitad acent to which the core receptacle is provided with a core catcherl5. This core receptacle may be made any desired length depending uponthe thickness of the sectio that is to be cored.

In the embodiment shown in Figure 3 parts corres onding to those shownin Figure 1 bear the same numeral. This embodiment is designed forcontinuous coring while us ng the gas-lift princi le. To achieve this obective the upper end of the drill stem 3 is provided with a plurality ofsections US each of which is composed of two concentric nines. Theinner-p ne H has the same diameter as the drill stem, which in this cases ou d be uniform from the surface substant a l to the drill bit. Theouter pi e is s aced from th inner-pipe a distance sufiicient to providea passage for gas. In the lowermost sect on V. con u ts l8 connect theannular gas assage IS! w th t e inside of the inner-pipe l1. Th seconduits iii are s aced from each other perinh rallv so that a s tablenumber of inlet ports is r vided in the inner-nine I! to insure fairlyuniform distribut on of the as in said nine. The ab ttin ends of thesections 16 are li e ise rovided with peri herally s aced con du ts 2"which serve to conduct gas from one annular space I 9 to another. One ofthese abutting ends is provided with an annular channel 2! formin a sortof man fold with which the conduits an in the abutting ends connect sothat actual alignment of these conduits is unnecessary.

In this embodiment as indicated above, the inn r bore of t e dril stemshould be uniform substantiallv throughout its length. In order tofacilitate the floating of the cores to the surface, there s provi ednear the end adiacent the core bit 22 a wed e-like member 23 affixed tothe inner-wall of the drill stem having its pointed end. down ard. Asthe core 24 moves upwardly in t e drill stem, its u per end slides alongthe inclined plane formed by the wedge member which has an inclinationsuch as to cause a portion of the core to break off as its upward movement continues.

In Figure is shown a modified form of the arran ement for breaking upthe core into short len ths. In this case there is arranged in the drillstem 3 as a continuation of the central passage of the core bit 22 abent pipe 25. As the 4 core moves upwardly through this pipe, it isdeflected from the vertical in such a manner as to break into segmentsof appropriate lengths. Upon leaving this pipe the segments of the corpass upwardly through the drill stem. At the upper end of the drill stemin the continuous coring embodiment there is connected to the swivel 6 agoose-neck 25 which discharges drilling fluid and core segments from itsopen end onto a screen 2l arranged in a vessel 28 and spaced from thebottom thereof whereby drilling fluid passing through such screen mayleave the vessel by conduit 29 which discharges into the mud pit.

Gas for the lifting of the drilling mud is admitted into the annularchamber I 9 by a duct 30 connected to a swivel gland 3! on which theflange 32 on the upper end of the outer pipe of the uppermost sectionsit rests. The swivel gland in turn rides on a flange 33 carried by acollar connected to a packing gland 35 mounted on the drill stem.

As previously indicated, in the practice of the present invention, onecan employ as many sections 16 as desired. The uppermost sections 16.

including the swivel air gland and the packing gland may be a very shortsection which remains permanently attached to the Kelly and sections I6is included in the stem, and circulation of the drilling fluid bygaslift begun. It is clear, of course, that this can be started earlier.

It will be appreciated that the method and apparatus of the presentinvention are susceptible to many changes without undergoing any changein essential character. This invention provides not only theconsiderable advantages heretofore listed of avoidin difificultiesusually attending reverse flow circulat on of drilling fluid, but inaddition eliminates the need for large expensive mud pumps, In view ofthe fact that the method of the present invention does not depend to anygreat extent on the viscosity of the drilling fluid for the lifting ofcuttings and cores, it is desirable to utilize a driling fluid having astrong suspending power, such as, one including a highly colloidal clay.If desired, the lifting action of the drilling fluid may be augmented byutilizing a wellhead and applying a small amount of pum pressure to themud fed into the annular space between the drill stem and the bore holewall. In addition mechanical de-aerators may be employed at the surfacefor facilitating the removal of the gas from the mud. Conventionalweighting agents and other mud addition agents may be used in thepractice of the present invention.

The nature and objects of the present invention having been thusdescribed and illustrated, what is new and useful and is desired to besecured by Letter Patent is:

1. A drilling apparatus for the continuous coring of earth formationsencountered in drilling a borehole comprising an upper portion of drillstem consisting of a plurality of threadedly combined gas conductingdrill pipe sections, each section being composed of two concentric pipesdefining between them an annular passage for gas, solid ring portionsjoining said concentric pipes at their ends and closing oif said annularpassage, at least one of said ring portions being provided with anannular groove on its exposed side, peripherally spaced conduitsextending through said ring portions longitudinally of said concentricpipes and in substantial alignment with said annular grooves so that thespaced conduits in abutting gas conducting drill pipe sections willcommunicate with said annular grooves, a lowermost gas conducting drillpipe section provided with a plurality of ports substantially uniformlyspaced peripherally in the wall thereof and establishing communicationbetween the annular groove in the end of the abutting gas conductingdrill pipe section and the central bore of said lowermost gas conductingdrill pipe section, a lower portion of drill stem comprisingconventional drill pipe attached to said lowermost gas conducting drillpipe section, a core bit attached to the lower end of said conventionaldrill pipe, a core-breaking wedge member afiixed to the inner wall ofsaid conventional drill pipe at a point intermediate said core bit andsaid lowermost gas conducting drill pipe section, means for introducinggas into the annular gas passage in the uppermost of said gas REFERENCESCITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,071,199 Andrews Aug. 26, 19131,280,159 Carmichael Oct. 1, 1918 1,283,662 Carmichael Nov. 5, 19182,034,072 Wright Mar. 1'7, 1936 FOREIGN PATENTS Number Country Date26,451 Great Britain Nov. 25,1911

